


Love's Formula

by KaijinKyn



Category: Hatoful Kareshi | Hatoful Boyfriend
Genre: Backstory, Character Death, College, Detective AU, Established Relationship, Implied/Referenced Sex, M/M, Teacher-Student Relationship
Language: English
Status: Completed
Published: 2018-03-14
Updated: 2018-03-14
Packaged: 2019-03-31 10:55:49
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,327
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13973571
Author URL: https://archiveofourown.org/users/KaijinKyn/pseuds/KaijinKyn
Summary: “Souma.” Ryuuji’s voice was kind and gentle as he reached across the table to tangle his fingers with Souma’s own, the younger blushing hotly at the touch. He wasn’t used to this, thisintimacy.The other had called him ‘Souma’ without even thinking about the change. “We’re boyfriends. Boyfriends call each other by their first names and go on dates and kiss each other. Don’t you want that?”“Y-Yes, of course, but I… I don’t know how.”





	Love's Formula

**Author's Note:**

> SO THIS IS FOR AN AU  
> a detective au, to be precise  
> for some context, shuu is a world-renowned murderer who got arrested a few years ago by yuuya, a secret agent and rising star in his field. hitori, a detective working for a less-than-ethical company, chooses to enlist shuu's help in solving a fresh murder case, based solely on the fact that the new murders are lifted directly from shuu's own methods - and the fact that hitori believes shuu can help him find his long-lost brother... provided shuu is on his best behaviour.  
> ANYWAY THIS IS SHUU'S BACKSTORY FIC LMAO  
> i wrote it a while back but never published it so. hope it's alri g h t-

“Heeey, Isa!” A heavy hand on his shoulder, the familiar scent of cigarette smoke and chemicals quickly filling Souma's nose. Ryuuji was back.

“Hello, Doctor. Did you have a good trip?” Souma didn’t look up from his work as he spoke - he never did, not even for Ryuuji. Only an idiot would stop paying attention to what they were handling, lest it blow up in their face. Souma was handling cells, which weren’t weren’t _particularly_ known for their explosive natures - but if he looked away for even a second he could miss an important reaction of some kind, so it was simply useful to pay attention.

Ryuuji, of course, didn’t care, bouncing around Souma so he was sitting across from the student and, resting his chin on his folded arms, watched Souma with an expression that could only be described as ‘complete adoration’. Such a gaze never failed to make Souma feel incredibly embarrassed and he knew from the widening of Ryuuji’s grin that there must have been a pink dust on his cheeks.

“Y’know, you can call me ‘Ryuuji’! We are dating, after all. Don’tcha think it’s a little weird to keep calling me ‘doctor’ and ‘sir’?”

“Well, you are technically still my professor, no matter our relationship with each other outside of work.” Souma grumbled in reply, swapping one swab for another and peering into the microscope before him. Nope… Still nothing. Did the students in this university have the world’s most resistant immune system or something? It was like they’d never caught a cold in their lives - or perhaps they washed their mouths out with soap. “You still call me ‘Isa’.” Was that a slightly sour tone to Souma’s voice, perhaps? From across the table Ryuuji smiled that same familiar smile he wore when he was teaching and Souma frowned in return, feeling patronised already. It was bad enough he was dating someone far above his own mental capacity, even if the other didn’t act like it sometimes - he didn’t need Ryuuji actually showing it.

“Hey, don’t be like that! I’ll call you ‘Souma’ if you want, I just thought you were more into the whole ‘formality’ thing.”

“I am.” Souma sighed, giving up on his work and setting it aside to look at Ryuuji properly, blank violet eyes hiding vulnerability behind them. “But, try as I might, it feels… Wrong, to be formal with you.”

“Then don’t worry about it!” Ryuuji replied cheerfully, amused smile so wide it forced his red eyes into a squint as Souma’s frown only deepened, confusion visible on his face.

“But-”

“Souma.” Ryuuji’s voice was kind and gentle as he reached across the table to tangle his fingers with Souma’s own, the younger blushing hotly at the touch. He wasn’t used to this, this _intimacy._ The other had called him ‘Souma’ without even thinking about the change. “We’re boyfriends. Boyfriends call each other by their first names and go on dates and kiss each other. Don’t you want that?”

“Y-Yes, of course, but I… I don’t know how.” Souma’s voice trailed away as he spoke until it was almost nothing by the end, cheeks nearly as red as his glasses. Much to his embarrassment, Ryuuji outright laughed at him, the partridge squeezing his eyes shut and sinking slightly in his seat as Ryuuji’s hand left his. That was it, the other wasn’t interested anymore, Souma had ruined things for himself once again-

Arms wrapped around Souma’s shoulders, the younger opening his eyes in surprised confusion as that familiar, comforting smell encompassed him. “Doct- ...Ryuuji?”

“Honestly, Souma, you’re too cute!” Ryuuji looked down at his red-faced boyfriend in amusement, a hand moving up the back of Souma’s neck to tangle fingers in brown hair before rocking on his heels, rocking Souma gently at the same time as he did so. “I’ll teach you how to love, don’t worry. Then once you get your doctorate you can pay for all our stuff with the money you’ll have from being a super cool doctor!!”

“Hm… You sound like you already have everything planned out.” Souma wasn’t going to complain, he barely knew himself what he wanted to do with his life. Spending it with Ryuuji, though… That sounded nice.

Getting to his feet, Souma moved to wrap his own arms around Ryuuji’s waist in a slightly awkward hug from the shorter bird, pressing his face to the rock dove’s neck. “Thank you.”

“Aw, no need to thank me, Souma! I just love ya, that’s all.” Ryuuji smiled, moving to gently cup Souma’s chin with a hand, tilting his head up and- _Oh._ Okay then.

Fingers curling in surprise around the back of Ryuuji’s neck, Souma found himself leaning into the kiss, eager for Ryuuji to teach him. He’d always thirsted for knowledge, always wanted _more_ \- if this was what he was going to get in terms of teaching then he’d in no way complain.

For a moment after the kiss, there was a gentle silence between the two of them, Souma’s arms still wrapped around his boyfriend’s waist. “...You didn’t answer my question.” The silence was broken by Souma’s quiet words, Ryuuji blinking owlishly above him for a moment before starting to laugh, wrapping his arms around Souma in his own tight hug and holding the increasingly flustered partridge close to his body.

“Souma, you’re too cute! I love you, I love you, look at you-!” Another kiss that ended before it could even begin, Ryuuji releasing his dazed boyfriend from his grip and throwing his hands in the air with a grin. “The trip went great!!”

Looking up at the other in confused wonder, Souma shook his head after a moment to clear his mind, watching Ryuuji bounce out the door, probably off to bother one of the other science professors.

He was in love with an _idiot._

 

* * *

 

“...Heeey. Soumaaa. Wake uuup.” A warm hand on his thin waist, the smell of smoke and sex lingering in the room. Groaning quietly, the partridge turned so his face was pressed to his boyfriend’s bare chest, a soft chuckle from the other sending shivers down Souma’s spine. What he wouldn’t give to stay like this forever… “Souma, you’ve got class today.” Another groan, Souma curling closer to Ryuuji despondently. He didn’t want to. It was boring and work was a chore and the bed was warm and Ryuuji was _warmer._ “Souma.”

“Don’t make me, Ryuuji…” From above him the dove sighed, pressing a soft kiss to the top of Souma’s head and making the partridge’s toes curl pleasantly under the covers they shared.

“Souma, you’re never gonna be a doctor if you don’t work for it.” He _knew_ that. He also didn’t care. Ryuuji was better than some stupid doctorate. Ryuuji was fun, Ryuuji was entertaining, Ryuuji was perfect. He could fail all his classes and he wouldn’t care, so long as Ryuuji was at his side. “...I have to teach today.”

“Nnn...” Souma whined, properly curling his arms around his boyfriend as if trying to keep him in place, not that he needed to bother - Ryuuji wasn’t going anywhere, at least not yet. “Stay here, please…”

“I’ve got students to teach about cool stuff! They love my lectures just as much as you do.” Doubtful. Souma loved Ryuuji more than anyone could ever hope to. The way he smiled as he talked about what he was interested in, the pure passion behind his eyes and words, getting increasingly excitable and bouncy; Souma missed seeing Ryuuji teach. He was beautiful like that, so cheerful, so happy. “Souma, you _need_ to go to class.”

“‘S not important…” Souma mumbled, tucking himself even closer to Ryuuji - only for the other to move suddenly, shifting so he was angled over his boyfriend's body, arms either side of Souma’s head and looking down at him with a soft expression. Souma blinked up at him blearily in response, unable to really see much of the other aside from his bright eyes without his glasses. “Ryuuji…”

“I’m not gonna make you go, Souma, but…” Ryuuji bent down, pressing a soft kiss to his boyfriend’s neck gently and then carrying on over his shoulder and collarbone, Souma making a noise of appreciation at the attention. Ryuuji didn’t want to leave either, it seemed. “They’ll kick you out if you keep bunking.”

“Don’t care.” Souma muttered, curling his arms under Ryuuji’s own and pulling him down, their warm foreheads pressing together before anything else did, soft lips meeting and one calloused hand moving to slide down to Souma’s hip, the partridge huffing against Ryuuji’s lips appreciatively before speaking. “I want to stay here… I want to be with _you_. Can’t we just lie in bed and have sex and do nothing all day?”

“Hah, God, Souma. I wish.” Their hips met, Souma whimpering softly with want in response and making Ryuuji’s eyes widen slightly at the sound. They really didn’t have time to do this, but he’d be lying if he said he didn’t want to. “There’d be no bed if I didn’t go to work.”

“Just- Please-” Souma’s voice was warbled, his need becoming all too apparent - it didn’t take much to get the partridge going. “I’m not going to class, just- Leave me something to remember you by while you’re gone-” Ryuuji’s lips twisted into a smile at that, eyes softening. Souma was absurdly cute. Saying things like that should be illegal.

“Fine, fine, if you insist…” Kissing down Souma’s chin and back to his neck, Ryuuji gave a quick lick to salty skin before biting down suddenly, Souma jerking beneath him with a half-pleasured, half-pained cry, fingernails digging into Ryuuji’s shoulders. The dove knew his boyfriend well; how he got off to pain, especially his own. Strange, but nothing Ryuuji couldn’t grant him - he knew where and where not was safe to harm.

“Nn, Ryuuji-” Still, as much as the rock dove wanted to stay, he couldn’t. Pressing a gentle kiss to the wound he’d just made and licking at slightly bloody lips afterwards, Ryuuji slid away from Souma and out of the bed, the partridge left watching him sullenly from the sheet. “You’re so cruel, Kawara.” Ah, his last name. Sending Souma an apologetic smile, Ryuuji pulled yesterday’s dress-shirt on from off the floor, entirely unbothered by the creases and wrinkles. At least it was _clean;_ that was a feat in itself for the haphazard rock dove.

“Sorry, Souma. I’ll bring you back something cool from lesson, kay?” The partridge rolled his eyes in return, sitting up in bed a little and touching gingerly at the bite on his neck. Ah, painful; he’d need to disinfect that soon. Souma couldn't complain, it was what he’d asked for - he was hard now, though.

“You don’t have to, if it’s inconvenient.” For a moment Ryuuji looked like he was going to argue, Souma cutting him off with a gentle look before he could even begin. “I hope you have a nice day. I love you.” For a split second Ryuuji looked stunned - before borderline jumping onto Souma again, the shorter male squeaking in surprise as his face was assaulted with kisses, warm hands on his cheeks and holding the partridge’s head in place.

“Souma!! I love you too!!”

In the end, Ryuuji _did_ end up late to work, hair and clothes a mess and soft hickeys along his wrist that he laughed off when people asked after.

 

* * *

 

“Hey, Souma.”

“ _Ryuuji-_ ” He couldn’t see. He had his glasses on, why couldn’t he see? What was this film across his eyes, the wetness on his cheeks, the blurred distortion of Ryuuji’s perfect - _pale_ \- face? His chest had hollowed out a while ago, leaving him with nothing but an empty feeling in his bones. This wasn’t real, he was dreaming, he was- He was-

Sitting in a cold, hard chair by Ryuuji’s side, who was lying near-lifelessly in a hospital bed.

“Souma, don’t cry.” Warm hands on his face, brushing away that horrid wetness and allowing Souma to see Ryuuji - upbeat, smiling Ryuuji, even on the brink of death.

“How… Can you tell me not to, when you're…” He couldn't say it, he physically couldn’t make the words leave his mouth, catching horribly in his throat and resulting in a harsh sob from the partridge, covering his mouth with a hand afterwards. “Why… Why you? Of all people, why did it have to be you?” Ryuuji’s expression was calm, his dwindling time apparently not bothering him at all. Souma envied him; how he wished to return to his childhood apathy if only to stop feeling like _this._ Ryuuji had taught him love too well.

“We both knew this might happen, Souma. Hereditary illnesses kinda suck, huh?” He laughed, the noise mirthful despite its weak force. “You’re a doctor… You shouldn’t wish for other’s misfortune; that’s unprofessional.”

“I don’t _care,”_ Souma sobbed, his words catching and sounding far too mournful, even to his own ears. “I never cared about being a doctor, I just wanted _you_ and now you’re- Ryuuji, what do I do without you?”

“C’mon, Souma, don’t talk like that… You’ve always been such a smart man. It’s, hah, one of the many, _many_ reasons why I love you. You could find so many things to do.” Ryuuji’s eyes - red, so red, always so kind, so calm - were lidded, those gentle fingers that were still on Souma’s face gently drifting down his cheek, brushing along the underside of Souma’s jaw as he spoke. “Finish school, Souma... Be a doctor. Help people out.”

“...I can’t.” Souma whispered in reply, reaching up to hold the hand on his face still, eyes slipping closed in his grief. “I can’t do it without you. Ryuuji, I can’t, I can’t…” The partridge knew he wasn’t listening. There wasn’t anyone there anymore. Just a corpse with lifeless, kind red eyes and a slowly cooling hand that was limp in his own.

He hadn’t even said goodbye.


End file.
